Metal cation cross-linked 3D frameworks of Fe3O4 nanospheres encapsulated in graphene nanomesh with enhanced anode performance for lithium-ion batteries

Transition metal oxide (TMO) particles encapsulated in graphene shell has been reported to be an ideal lithium-ion batteries (LIBs) anode due to its well TMO particles volumetric adaptability upon cycling. In this paper, to further enhance the structural stability as well as electrochemical performance of Fe3O4-based electrodes for LIBs, 3D composite structures of Fe3O4 nanospheres (NSs) encapsulated in interconnected holey graphene nanosheets (Ca2+/p-rGO@Fe3O4) were fabricated by facile hydrothermal process using Ca2+ as crosslinker and hydrogen peroxide (H2O2) as etching agent. The composite was characterized by X-ray diffractometer (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Fourier Transform Infrared Spectrometer (FTIR), and other test methods. The morphological and structural tests show that Fe3O4 NSs are homogenously embedded in the 3D framework of interconnected graphene nanomesh aerogels. Based on its unique structure, the Ca2+/p-rGO@Fe3O4 composite electrode delivers an initial discharge and charge capacities of 1288 and 783 mA h g−1, respectively, remarkable rate capability at current densities from 0.1 to 2 A g−1 and excellent cyclic stability with respect to that of its counterparts Ca2+/rGO@Fe3O4 electrode, p-rGO@Fe3O4 electrode and rGO@Fe3O4 electrode, which are prepared using a similar synthetic procedure but without the addition of H2O2 or CaCl2 or neither. It is proved that the synergistic effects of Ca2+-induced crosslinking reaction at the edge of GO nanosheets and in-plane pores on graphene coated on the surface of Fe3O4 can enhance the whole electrochemical performance of anode for LIBs.